MICROTOMES....EYE SECTIONING.....and CRUEZTFELD-JACOB

From:

"Timothy R. Wheelock"

Hi All: 3 issues
MICROTOME
Thank you for your continuing advice on microtomes, particularly
regarding the issue of blade holder problems.
Dawn, I have not tried the Surgipath machine yet. I would be interested
in hearing of your experience with it.
David, thank you for the info on Microm's updated blade holder; I will
ask the sales rep about trying it out.
Andi, thank you for the extensive, thoughtful response, from the sales
rep's perspective, on demo equipment wear and tear, and asking the
companies for what you need.
Troy, thanks for pointing out blade holders as the weakest link on
microtomes. It points to a universal problem, not necessarily attached
to any one brand of machine.
EYE SECTIONING
John, I actually use a cold and heated water bath with brain tissue. The
cold bath is used to examine and pick out the best sections for your
slide. The heated bath is for spreading the tissue out flat, getting rid
of wrinkles. I lift the chosen section onto the the albumin-coated
slide, transfer the section onto the heated surface, then pick it up
again a second or 2 later onto the same slide.
With brain tissue, especially cortex, trying to accomplish both tasks
at once on the heated bath can be difficult, because in the time it
takes you to choose the section and extricate it from the ribbon, the
section you want can expand too much to the point where it will no
longer fit on the slide, or two adjacent cortical areas will drift
away from one another more than they have to, or the tissue can
actually fly/break apart on the bath. By doing the choosing and ribbon
slicing on the cold bath, you minimize the time needed on the heated
water surface.
Also, a student of mine came up with another trick. If you have a piece
of tissue that has a tendency to fly apart on the heated water (it could
be a processing problem), pick the tissue up on a slide from the cold
bath, then lie the slide on the surface of the heated water (the tissue
never comes in contact with the water). The thin layer of water between
slide and tissue will slowly heat up and slowly flatten the tissue.
This technique gives one great control of the flattening process. It's
great if you have, say, 8 pieces of spinal cord in a block. This sort of
section can be a nightmare, with pieces of cord flying off in different
directions. But with the heated slide technique, it becomes manageable.
JACOB CRUEZTFELD DISEASE
Curt, we see CJ less than once a year. We take in about 300 cases total
per year. This Brain Bank opened its doors in 1978. The first few years
were slow, so I would guess we have seen around 15 cases. When our
neuropathologist makes the diagnosis, we send the report, and all the
fixed and frozen tissue to a researcher at the NIH who specializes in
studying CJ.
Tim Wheelock
Brain Bank
McLean Hospital
Belmont, MA